Idiots guide to 8 spd trans rebuild

[dgjks6 6]

OK - I am starting a thread here because my restoration thread is getting long and I want to chronicle my transmission rebuild because

1 - I'm an idiot

2 - I can remember how to do it

3 - I need help

4 - maybe this will help someone in the future

I have two transmissions - and neither work - one broke an axle and when taking it apart I did not follow the instructions and gears went everywhere. The second - which is what the pictures are of - is a transmission that has been worked on before, but after getting it apart the gears get caught - it feels like there is a piece of metal somewhere in the gears - So I am taking it apart.

I have tried to follow the manual - and not being as mechanically inclined as most of you here - and not being able to read all of the pics on the manual I downloaded - I am goignt o sentence by sentence diagram how to disassemble and reassemble a transmission. I have looked at the other threads and they are to advanced for me.

There are 26 steps to disassemble an 8 spd transmission. Through shear stupidity and luck I finished the first 10 steps. this involves getting the transmission off the tractor and getting it split in half. I was actually able to follow the directions for that and do not have step by step pics.

So we are going to step 11:

Shift the 2nd and high shift fork assembly up into the 2nd speed position.

I have no idea what this means so please someone tell me. I have included the pics below, but I need to know what is high and what is 2nd.

High gear - the screwdriver is in the low/high shifter. Left is low and right is high, so therefore:

And low gear

Neutral:

So I am good so far, but now what is what?

front shifter up: what gear?

rear shifter up: What gear?

front shifter down: What gear?

rear shifter down: What gear?

Let me know and I will go to step 12.

[dgjks6 6]

So having the patience of a gnat - i could not wait for a reply. So I stared at the manual and came up with this for step 11

This is my version of step 11. This is the more rear shifter fork all the way up:

Then in step 12a

I remove the cluster grear and brake shaft assembly:

It just comes right out.

Sow now to step 12b: remove the reverse idler gear and shaft.

Is it this?

or this?

Stay tuned

[dgjks6 6]

OK this is getting good - but have no fear - it does turn into a typical project for me.

So I decide this is the reverse idler gear and shaft and remove it:

STEP 13 - remove large reduction gear assembly:

easy enough - post 73 has a thrust washer:

STEP 14: remove splined pinion gear from the input shaft:

STEP 15: With a screw driver remove the plug from the detent passage:

here is the plug - looks like a gob of silicone

next the dreades step 16

[dgjks6 6]

STEP 16: Place the shift forks in neutral and remove the low and reverse rail and fork assembly (nearest the end of the case) with the sliding gear, making sure to catch the stop ball and other detent parts as the shift rail is removed:

back in neutral:

then just pull on the shaft - with some wiggling it will come

Now here is the problem -

never saw the stop ball or detent parts

So I go to step 17

STEP 17 - remove the 2nd and high shift rail fork assembly with the 2nd and high sliding gears

STEP 18 - remove the remaining detent parts - ball, spring, and stop pin from the passage

But I can't get out the stop pin - how do you do this?

[dgjks6 6]

So far lost the spring and ball of the low shifter fork and the pin for the high shifter fork I can't get out - So I go to step 19

STEP 19: remove the gear and spline assembly from the input shaft

STEP 20: remove the input shaft:

I try and no luck - flip the trans over and I see this:

the key is stuck in the key -

HOW DO I GET THIS OUT? tried and tried and no luck - so here the journey ends for now

except...

I found the problem with the transmission:

this was floating around in there:

and I'm guessing it's not supposed to be like that.

[dgjks6 6]

So here are my questions:

1-what did I lose when I took out the low shift rail? A ball and spring? Where are they?

2-how do I get the pin put between the two shift rails?

3-what is that broken thing

oh - and how do I get the key out without damaging anything?

I will check back for answers, but I may go back out and work some more on it

[rmaynard 15,631]

Think about your transmission from the position that it would be in as you sit on the tractor. With the shift lever inserted, the shift lever is pulled to the back and to the right, that is first gear. Which means that the front shift fork will be moved to the left.

Reverse is back and to the left, meaning that the front shift fork will be moved all the way to the right. Second gear is forward and to the right, meaning the rear shift fork is moved to the left, and third gear is forward and to the left, meaning the rear shift fork is moved to the right.

Bob

[dgjks6 6]

Think about your transmission from the position that it would be in as you sit on the tractor. With the shift lever inserted, the shift lever is pulled to the back and to the right, that is first gear. Which means that the front shift fork will be moved to the left.

Reverse is back and to the left, meaning that the front shift fork will be moved all the way to the right. Second gear is forward and to the right, meaning the rear shift fork is moved to the left, and third gear is forward and to the left, meaning the rear shift fork is moved to the right.

Bob

thank you - that makes sense. I am starting to see how these things work now. In my mind I had it backwards. I guess that means the rear rail up is second - and I guessed right.

Better to be lucky than good.

[rmaynard 15,631]

With the transmission open and in the position that you took the pictures, you are correct. Up would be the same as left. Down would be the same as right.

Bob

[Duff 206]

The broken sheet metal thingy you are holding looks like the hi-lo shift fork. They are notoriously thin and can wear out or break very easily, which is why I've read here time and again NEVER shift ranges while moving or force the shift lever. Fortunately, they are (or were recently) still available and not that expensive.

That little stop pin thing can be a real PITA. If you've got access to one, try a strong magnet.

The detent ball and spring are slippery little (emphasis on little) cusses and can go flying without you even knowing they went, let alone where. But chances are they are in the bottom of the tranny in behind something. I found mine after fishing around for awhile. Again, a magnet (one of those strong ones on the end of a telescoping probe like professional mechanics use) could be your best friend.....

Duff :thumbs:

[Duff 206]

Now to that stuck key......I would try very carefully cutting a small cross-wise slot in the end of the key with a Dremel tool, as close as possible to the shaft, so you can get a screwdriver into it to pry it out. Oh - make sure the shaft is pushed back out of the tranny as far as it will go before you start prying.

Actually, looking at your picture, it appears the shaft has slipped or been driven part way into the transmission and the bearing or oil seal may be holding the key from popping out. Am I making any sense to anyone but myself?????

Duff :thumbs:

[C-Series14 15]

Now to that stuck key......I would try very carefully cutting a small cross-wise slot in the end of the key with a Dremel tool, as close as possible to the shaft, so you can get a screwdriver into it to pry it out. Oh - make sure the shaft is pushed back out of the tranny as far as it will go before you start prying.

Actually, looking at your picture, it appears the shaft has slipped or been driven part way into the transmission and the bearing or oil seal may be holding the key from popping out. Am I making any sense to anyone but myself?????

Duff

Makes sense to me. Looks like it is pushed in the case...

[dgjks6 6]

no, the key is not in the case. I can move the input shaft up and down until the key gets blocks it from going any further. The key has a bolt make in the side. Is aooears they overtightened the bolt on the key and pushed it in.

No dremel here. Lost the motor while doing drywall. Too much dust. But I have a hack saw!

[Duff 206]

no, the key is not in the case. I can move the input shaft up and down until the key gets blocks it from going any further. The key has a bolt make in the side. Is aooears they overtightened the bolt on the key and pushed it in.

No dremel here. Lost the motor while doing drywall. Too much dust. But I have a hack saw!

Aaah! So the bolt effectively expanded the key and jammed it in the keyway? Makes sense, unfortunately.

I'd still try the slot and screwdriver trick first, and if that doesn't work you may have to borrow a Dremel from a neighbor and very carefully grind the key out of the keyway. Others may have a better idea for you.....

Duff :D

[dgjks6 6]

So I flip the trans over and shake it to see what falls out. No balls, but the pin comes out. So verify this for me guys. Between the 1-2-3-R shifts rails there is a a spring, pin and 2 balls. The other hole on the side of the trans is to push them back in, but noting goes in that passage . hence why it was sealed with silicone?

So I have a spring, a pin and one ball.

Luckily I have 2 more balls.

in the other transmission

So to the key:

cut a slot with a hack saw and with some finesse...VICTORY

Thanks Duff and C Series 14

Step 20: Remove the input shaft

done

STEP 21: Remove the sliding gear from the high low range shift lever-

WHAT? Never seen or heard of this gear.

After the input shaft came out there was just a washer

Need a little help here.

STEP 22: remove inout shaft thrust washer. No problem. Also, no picture, but trust me there was one there

STEP 23: Remove the high low range detent bolt and shift assembly

No problrm

STEP 24: remove the detent bolt from the shift fork being careful to catch the stop ball and spring.

Lost here. What do they mean. I see no other balls or springs

Step 25:

Remove reduction gear by driving it out toward the inside of the case and remove gear

STEP 26: Remove the high low range shift lever and shaft from inside the case.

Actually I did this from the outside with a hammer

AND FINALLY DONE

[dgjks6 6]

So to my final questions.

1 - 2 balls, a pin,and a spring between the shift rails. nothing in the detent passage?

2- Where do the spring and the ball go for the hi-low shift fork?

3- STEP 21: Remove the sliding gear from the high low range shift lever.

What is this step and gear and how did I miss it?

[The Toolman 22]

Next time ya got a key stuck, just use a pair of cutting pliers/dykes an squeeze them hard on the key length wise an pry up. A lot simpler....

[stevasaurus 22,882]

Great pictures. Just to make it easy for anybody else. In your first pictures the right shift fork is your 1st and reverse...down is reverse and up is 1st gear. The left shift fork is your 2nd and 3rd gears...up is 2nd and down is 3rd.

If you look at both shift forks below the gears, you will see notches in the shafts. When in position the ball-spring and pin-ball fit between these two shafts. The ball slips into one of the notches and holds the forks in gear. So...yes they all fit between the forks.

The access hole is only that...your trans is bolted up to a backing plate on the horse, so you really don't get any leaks. I would fill it with fiber grease in stead of silicone when you put the trans back in.

If you lost one of the balls...they are 1/4" ball bearings and ACE hardware sells them one at a time if you want. For the .25 cents apiece...replace both.

The inside of your trans looks great...nice and clean. Keep up the good work.

Also...you are correct about the reverse idler...if you noticed...the bevel of that gear is up. It is important that you put that gear in the same way. It will not shift smooth if you have the bevel down. :D

[dgjks6 6]

If I get time I am going to do this thread again with the correct steps in the correct order.

So I have two transmissions. I could not figure out step 21 - remove sliding gear from input shaft.

Now that I have a transmission with an intact high-low fork I fould that the sliding gear in held down by this. By since the fork was broken with the first transmission the sliding gear came off with the other gears on the input shaft.

so here is the correct removal of the input shaft

and then the sliding gear from the high - low fork

and then the washer - notice here that the fork is intact?

[rickv1957 72]

Tranny looks to be in good shape overall,Rick

[WH854 44]

Is that hi-low shift fork P/N 116636-03 I may need one on my rebuild?

Chas

[dgjks6 6]

yep. thats it

make sure its the same trans. this one had 1 inch axles. not sure if the same for 1 1/8 inch trans.

[Coadster32 793]

Nice write-up. Thanks for doing it. :thumbs:

[WH854 44]

That HI-LOW SHIFT FORK P/N 116636-03 from Toro is $38.00

Chas

[noncritical 5]

would this be the same as in a 1985 312-8 mine just locked itself in low